Chosen Solution
I have a macbook pro early 2015 edition. My device while logging in shows keyboard and trackpad not found. I have tried SMC reset, PRAM reset. I have got the cable changed and the service center had changed the topcase as well. Yet this issue has come up again for the 6th time in 2 years. The only key that works is the power key. Command and shift keys work only while booting but once the login screen shows up they do not work. I have even deleted the pList files. I somehow feel its not a hardware issue. What else can i try now?
I would start off by replacing the Trackpad ribbon cable. Often times the battery presses on the cable and over time breaks down. Here’s the needed part: MacBook Pro 13" Retina Trackpad Flex Cable, Early 2015 and here’s the IFIXIT guide you’ll need to follow MacBook Pro 13" Retina Display Early 2015 Trackpad Replacement Follow the steps till Step 7 then jump down to Step 17 to 20.
